Brake centralizer



June 24, 1930. T. P. CHASE BRAKE CENTRALIZER Filed Jan. '21. 1929 2 Sheets-Sheet l 3mm jm w (Z 11 June 24, 1930. V P CHASE 1,768,509

BRAKE CENTRALIZER Filed Jan. 21, 1929 .2 Sheets-Sheet 2 v I! gwuvntcw dummy Patented dune 24,. 1 I:

unrr s'm'ras orricn TnERon R oHAsE, or DETRoIT, MICHIGAN, AssIenoR To GENERAL MOTORS REs ARoR: coRroRATIon, E DETRoIT, MICHIGAN, A coRroRATIon or DELAWARE BRAKE CENTBALIZER Application filed Ianuary 2i, 1929; Serial 1T0. 333,974.

This invention relates to brakes. It has i been designedmore particularly for vehicle brakes, and relates tothe mechanism for applying the brake means to the rotatin member, rotation of which is to be chec ed, or stopped.

An object of the invention is to provide a structure whereby the applied pressure may be equally divided between the two brake means, and whereby the brake-applyin means is mounted for bodily movement an .to be returned to its neutral position after tralizer device detached.

Figure 4 is a view in elevation of a detail.

Figure 5 is a view in elevation of a modified form.

Figure 6 is a sectional view on line 66 of Fi ure 5.

i re 7 is a viewin elevation of a modified orm.

Figure 8 is an edge view of the form shown by Figure 7.

Referring by reference characters to the drawing, numeral 9 represents a conventional brake drum such as is attached to the wheels of vehicles. Numeral 10 represents a closure plate, or backing plate, which is relatively fixed. In the case of a front wheel, this'closure plate is secured to the wheel knuckle asby' fastening means 13. Another plate 15, which may be called the anchor plate, is located midway between the head of the drum'. and the backing plate 10. This plate 15 is secured by the same fastening means 13 to the knuckle. There may be an oil guard plate 17 attached to plate 15 by screws, or the like, 19.

The shoes, to frictionally engage the drum, are designated by numerals 21 and 23. Shoe 21 is the larger and is designed to be more effective to stop forward motion of the vehicle. It has an articulated anchorage as by the use of link means 25 pivoted to the shoe at one end, as at 27, and to the anchor plate 15 at the other end, as represented by numeral 28. The other shoe 23 is rigid throughout, and pivoted to the anchor plate at 31. The shoes are to be expanded into engagement with the drum, preferably by a cam 33 operably engaging parts carried by the shoes. To that end the two shoes have rockers 35 pivoted as at 37. Each shoe has a terminal slot 39 and pin means 41, carried by the rockers, move in the slots, the pin and slot permitting limited movement only, the purpose being to avoid sliding movement between the cam and the ends of the shoe. A spring 43 has its ends attached to each shoe and holds the shoe rockers against the cam, with the cam rotated into inoperative position.

It is with a construction such as described that this invention is associated. No invention is being claimed for that structure, it-

self. Itis well. known that in applying a brake the cam pressure should at all times be equally elfeotlve upon both shoes. If there be unequal clearance between the drum and the two shoes, the cam, when rotated, takes up the clearance of one shoe before the other. As a result, the resistance offered by that shoe to further cam rotation -makes quite high the pedal pressure suflicient to actuate the other shoe. To secure equal pressures, it has been proposed to float the camshaft so that it may move bodily toward the shoe having greater clearance. This floating insures equal pressure upon the two shoes, and has been adopted in this invention.

In some prior constructions no provision has been made to insure the return of the camshaft to its initial position. In other cases, arrangements have been made to auto-- the shoes may drag on the drum, for, while the releasing spring will hold both shoes on the cam, the two shoes with the cam are not,

w as a unit','supported from drum contact. The

present invention aims to permit that desirable free floating of the cam to secure equal division of the ap lied effort and to also insure a return of t e cam to its point of departure afterthe brake-applying effort has been released.

Within the drum enclosure is a plate 45. A bolt 47 passes through the backing plate 10, opening in the plate 45, and an opening in the anchor plate 15, as shown by Figure 2. A spacing sleeve 49 surrounds the bolt and extends from backing plate to plate 15. Plate 45 is formed with a slot 51 on an arc about 47 as a center, so that the said plate 45 may swing about 47 to a limited extent. A bolt 53 asses through this slot and a hole in the bac 'ng plate. A nut, not shown, may be used on the outside of the backing plate to cooperate with the bolt to hold plate 45 in adjusted position. Plate 45, at another location, has u wardly extending lugs 55. Swinging on olt 47 around the sleeve 49 is anarm 57,-sha d, as shown in'Figures 2 and 3. At the end 0 arm 57 there are hooks 59 with recesses 61 adjacent thereto. Fastening means, such as screws 63, secure flat springs 64 to each side of the arm adjacent the pivot 47.. The other ends of the flat springs are flexed and engaged under the hooks, as clearly shown in Figure 3. When the arm is in its neutral position, as in Fi ure 3, these springs engage the lugs 55, as lllustrated. It will be seen that the cam 33 is carried by a shaft 67 within a bushing 69 in an opening 71 provided in the arm. The opening in the closureplate is, as shown in Figure 2, of such dimensions as to give free swinging movement to the camshaft as the arm 57 swings about its pivot. Outside the closure plate 10 there is shown an element 73 keyed to the camshaft, and a stamped lever 7 5'rotatably mounted about the element 73. Suitable means, not illustrated in detail, may be used to adjustably secure arts 73 and 75 whereby manual rotation o 7-5 may serve to rotate the camshaft with the cam 33:

If Figure 1 be considered as showing the parts in a position of rest, a rotation of the cam will expand the shoes about their pivots and into drum contact. If, toefiect equalized pressure due to unequal lining conditions, or to the self-actuation of one of.the shoes, the camshaft arm 57 swings about bolt 47, one of the '3 rings 64 is further flexed b spring remains in contact with the hook 59 and moves away from its abutment 55. This action will occur'whichever way the arm 57 swings, as will be readily appreciated from an inspection of Figure 3. If excessive swinging of arm 57 occurs with every actuation of the brake, owing to a considerable difierence in lining thickness, this swinging may be avoided by the adjustment at 53. The

adjustment may be readily made by applying the brakes with the vehicle at rest, and loosening the fastening means at 53. The

unbalanced conditions of the two springs 64- will then automatically swing plate 45 to a position in which springs 64 are equally tensioned. The fastening means 53 is then secured in position and the brakes released.

It should be explained that the flat'springs 64 arebent initially so that when they rest on the hooks 59 they have the required amount of compression to hold the camshaft end of the arm 57 in centralized position with'the.

spring bearing against the lugs 55 of plate 45. It may be a matter of some difliculty to so dimension the opening between the lugs 55 that the springs will contact with both these lugs when engaged with the hooks. To overcomethis difliculty an adjustment may be provided atone of the lugs of plate 45', as I shown in Figures 7 and 8. Here one of the lugs is in the form of a threaded stem 81, and an adjusting stud 83 is threaded through the stem and secured in position by a nut 85 and a washer 87.

- In Figures 5 and 6 is a slightly different form which the invention may take. In this form a plate 91 is shaped, as shown. It is held by a bolt 93 and by the adjusting bolt 95, the latter passing through a slot 97 and held by a cotter pin 99. The plate has at its extremity an angularly bent flange 101 normally engaging at its ends the ends of leaf springs 103 secured by fastening means 105 to the opposite sides of a swin ing arm 107, the latter turnin on bolt 93 and carrying the camshaft as be ore. The leaf springs are flexed to engage abutments 109v on the arm 107 swinging of the member 107. The action is precisely the same as that described in connection with Figure 1.

I claim: 1. In combination, a brake drum, anchored shoes ,lto engage the drum, rotatable means y "to engage the adjacent ends of said shoes and engagement wit the abutment 55. The other expand them into contact with the drum, a pivoted member supporting said rotatable means at a position removed from its pivot, yielding elements terminally secured to said I pivoted member, one on each side of its pivot,

said yielding elements engaging, under tension, projections at points on said pivoted member removed from the pivot, rigid abutments engaging said yielding elements to flex one or the other of said yielding elements when the pivoted member turns about its pivot.

2. The invention set forth in claim 1, one of said abutments being adjustable.

3. In combination, a brake drum, brake shoes to engage the drum, a closure plate, a plate adjustably mounted relatively to said closure plate, an arm pivotally mounted relatively to said closure plate, leaf spring means to resist the pivotal movement of said arm relative to the adjustable plate, and brake- 5 applying means carried by said arm.

4. The invention defined by claim. 3, said leaf spring means comprising a pair of leaf springs held under tension by said arm, and abutments carried by said adjustable plate also engaging said leaf springs and serving to flex the one or the other of the same when the pivoted member swings to effect equalized pressure upon the shoes.

5. A centralizing brake-applyin device 21! comprising a plate having oppose lugs, a

camshaft carrying. arm pivoted for swinging relative to the first plate, a plurality of yielding means terminally secured at one end of each to said arm, the said arm constructed to hold the other ends of said yielding means, said plate abutments also engaging said yielding means whereby swinging of said arm additionally tensions one of said yielding means.

In' testimony whereof I afiix my signature.

THERON P. CHASE. 

